This invention is designed to solve not only the problem of preventing contamination caused by disposable syringes if they are reused by the users, since this is a current problem of world interest, this problem is completely solved with the syringes which render themselves unreusable, which are the subject of the aforementioned Patent Application, but this invention also provides the solution to the problem of the possible reuse of syringes by drug addicts, a problem which was not completely solved with the aforementioned syringes which rendered themselves unreusable.
The improvements set forth in this invention make the use of the syringes more effective and easier and prevent their possible reuse, even in a partial manner, as well as preventing the possible reuse of the injection needle. The aforementioned syringes could have their needles reused inasmuch as regular needles were used. For this reason, one of the aspects of this invention is to prevent the possible reuse of the needles.
My U.S. Pat. No. 3,667,657 shows a prefilled syringe in which a non-retractable knife destroys the syringe on use. There are some injectable solutions which cannot be stored for a given amount of time in containers made of material which can be cut with a blade, such as plastic or similar materials. For this reason there is a necessity for a syringe for these types of solutions which can be filled without the blade cutting the cylinder at the time that the solution is extracted from its container in the process of filling the syringe. My Mexican Patent No. 107,080 shows attaching a resiliently mounted knife to one of the sides of the flaps of the piston rod.
In view of the fact that in most of the foregoing embodiments, drug addicts can refill, even with a small amount of solution, the destroyed syringe due to the small part of the syringe which is not cut and which corresponds to the size of the piston of the plunger, this invention furthermore includes the following aspects that solves this and other problems.
In accordance with the present invention there is provided a disposable syringe which renders itself non-reusable which comprises a rigid cylinder coupled at one end to a bottom wall with an opening for the exit of the solution to be injected, and having the other end open, said end being integrally coupled to support flanges which extend outwardly and perpendicularly to the axis of the cylinder, and a plunger with a piston at the extreme end coupled to the cylinder, the piston having at least one punch rod which extends parallel to the longitudinal axis of the cylinder and is adapted to engage or puncture the bottom wall of said cylinder so as to prevent reuse.
One of the embodiments of this aspect of the invention, has in the forward part of the piston, a needle or pin which coincides with a weakened portion or groove made in the forward part of the cylinder without fully puncturing the wall of the same, in which case, when the solution is injected by the user and the piston reaches the end of its movement, the cylinder will be fully punctured in the said weakened section, preventing a possible reuse, however small it might be, of the syringe inasmuch as the syringe will be completely unusable. Of course this kind of destruction could be combined with the cutting blade which is outlined in the above models.
Another embodiment which solves the problem mentioned above has in the center and in the forward part of the piston a ribbed and toothed projection, or any other kind of mechanism which would jam when inserted into the needle on the first application of the solution, and it would stick in the ribbed part of the needle with which it would coincide, jamming the plunger with the needle, making any further reuse impossible. This embodiment could also be combined with the cutting blade as in my above mentioned application and would include a stop near the extreme end of the cylinder of the syringe container in order to prevent destruction of the syringe when being assembled before the first application, preventing the pin and the jamming mechanism from making the syringe unworkable prematurely.
These and other objectives to be obtained for the use of this invention will be better understood and appreciated by the reading of the following description which refers to the drawings of the preferred embodiment of the present invention.